Cervical cancer is the second most common form of cancer in women world-wide. Invasive cervical carcinoma develops by progression of less severe epithelial changes, known as dysplacia and cervical intraepithelial neoplacia (CIN I-II-III), into cervical carcinomas in situ (CIS).
Using vaginal aspirates (Pap smears), the epithelial changes can be detected and classified by common cytological methods. It is particularly important to notice that invasive cervical carcinoma is preceded by its dysplastic precursor lesions, which can be present for months or years before cervical carcinoma develops. Furthermore, progression to carcinoma can effectively be stopped by a simple operation (conization) if the precursor lesions are detected.
Many developed countries have experienced up to a 50% reduction in the incidence of and mortality from invasive cervical carcinoma after the introduction of organized screening programs. Despite this fact, about 500,000 women in the world are struck by cervical cancer each year. In the U.S., close to 5,000 women die each year from this disease. This number would drop further if more women were tested on a regular basis.
Of those who die of cervical cancer, 50% have not had a Pap test done in 5 or more years. Indeed, those women who do not participate in the gynecological health control and those who show false negative cytology are the highest risk groups for cervical cancer. The efficacy and reliability of the sampling method and the sample's analysis are therefore primary issues. This involves, in the first place, reaching those women who do not now participate in the gynecological screening by providing a simple and reliable device for sampling, and secondly, to increase the discriminating efficacy of the analytical methods to diagnose infections, precancerous lesions or cancerous lesions.
Association between papillomavirus (HPV) infection and cervical carcinoma was postulated in the 1970's. The International Biological Study on Cervical Cancer reported a world-wide prevalence of infection with HPV of 93% in women with invasive cervical cancer. In addition, the subtypes HPV 16 and HPV 18 are the most significant risk factors in its aetiology. HPV infection is also an important risk factor for progression of CIN.
Recent studies with improved methods of polymerase chain reaction (PCR) imply an overall HPV prevalence of almost 100% and that the PCR results correlate with the histological findings. These results reinforce the rational for HPV testing in combination with, or even instead of, cytology in population-based screening programs.
Determination of squamous intraepithelial lesions, or cervical dysplacia, is commonly used as an indication of progression to cervical cancer. Alternatively, the presence of HPV nucleic acid in a patient sample, following amplification by PCR, is taken as a risk factor for progression to cervical cancer. From the above, it is obvious that cytology and PCR analysis of HPV infection provide very efficient means to detect individuals at risk to develop cervical cancer.
Recently published evidence-based consensus guidelines for the management of women with cervical cytological abnormalities and cervical cancer precursors state that women with atypical squamous cells of undetermined significance (ASCUS) should be managed using a program of 2 repeat cytology tests, immediate colposcopy, or DNA testing for high-risk types of HPV. Testing for HPV DNA is the preferred approach when liquid-based cytology is used for screening.
The limiting factor in order to further decrease the incidence of and mortality from cervical cancer appears therefore to be related to reaching the non attending women and providing a simple sampling device giving relevant samples for HPV analysis and/or cytology.
Traditionally, sampling of vaginal smear requires scraping of a woman's cervix with a sampling device, such as a spatula or a brush. This sampling is generally performed by medical professionals like gynecologists, midwifes or nurses in a clinical environment. Many women, who now refrain from such gynecological testing, would participate if the sampling could be carried out at home and/or by the women themselves. Self and home sampling would therefore increase the participation in the gynecological screening, and by that means, decrease the incidence of cervical cancer.
In addition to the above, sampling systems are also in demand for DNA analysis. Law enforcement officials, paternity agents, etc. are constantly taking DNA samples to help solve crimes, determine paternity, etc. As the results of the tests done on these samples dramatically affect people's lives and may be desired as evidence in legal proceedings, the sampling must be done in a manner in which the sample contamination is reduced or avoided. As such, there is a need for an improved sampling system.